High frequency coupling system



DEC, 17, K SC E 2,225,!)85

HIGH FREQUENCY COUPLING SYSTEM Filed Oct. 23, 1934 0/7 lye/750a:

Patented Dec. 17, 1940 UNITED STATES 2,225,085 HIGH FREQUENCY COUPLING SYSTEM Kurt Schlesinger, Berlin, Germany, assignor, by mesne assignments, to Loewe Radio, Inc.', a corporation of New York Application October 23, 1934, Serial No. 749,511 In Germany October 27, 1933 12 Claims.

In the case of transformer couplings in connection systems in the television art, which operate with wide frequency bands, there. exists, as Well known, the difficulty that an even transmission of all frequencies is not readily possible. The subject matter of the present invention is a high frequency transmitter for television purposes and a circuit arrangement making use of the same.

In the drawing there is shown for example, diagrammatically, a transformer in conjunction with an amplifier tube. Fig. 1 shows a transformer having parallel damping resistances and Fig. 2 shows the same arrangement using damping by series resistances. In Fig. 1 2 is the primary coil and 3 the secondary coil of the transformer which is associated to an amplifier I. In Fig. 2 another embodiment of the arrangement in accordance with the invention is shown having a series damping by the resistances l0 and II which are connected in series with the windings of the transformer. There is to be transmitted a frequency band of f1-f2 periods.

It may occur, for example, that a 180-line television image, upon the scanning of which the a maximum frequency amounts to approximately 500 kilocycles p. s., is to be transmitted on an intermediate wave of'150'metres, the frequency band then extending'about a carrier frequency of 2 megacycles p. s., between 1.5 and 2.5 megacycles p. s., and having a width, therefore, of approximately 1 megacycles p. s. According to the in vention, in order that a band of this nature may be evenly transmitted, the coils 2 and 3 of the transformer are provided with a self-induction of such kind that their natural frequencies fp and f5 occurring in conjunction with the building-up capacities 4 and 5 are situated themselves outside of the band to be transmitted, viz., on different sides of the band for the input and output systems. Thus, for example, the primary natural oscillation f in the stated instance may be situated at a lower frequency than that which occurs, for example at .5-10 periods. There is then obtained according to the invention the advantage of an even'degree of transmission only in the event of the natural frequency of the secondary structure is being higher than the short-wave end of the transmission band, i. e., for example at 3-10 periods.

The basic idea according to the invention is also applicable to the opposite instance. A transmission of the band likewise even as regards phase and amplitude is accomplished when the primary coil is tuned high and the secondary coil low. Although in this case the degree of transmission is somewhat less than in the previous instance, it is nevertheless also possible by means of a transformer constructed according to an additional feature of the invention to obtain a '5 considerably improved transmission of a wider frequency band.

When the transmission frequencies approach the natural frequencies of one of the two coils disturbances occur in the television-image. Accord- 10 ing to the invention, these disturbances are avoided by the following measures:

1. By adjusting between the natural frequency and the next transmission frequency a proportion of 1.2 or more or .8 or less;

2. By connecting in parallel with the two windings damping resistances 8 or 9, which preferably amount to merely approximately of theresonance resistance of the windings when reaching their natural frequency, but are greater than the apparent resistance of the winding in operation. These resistances in the case of good transformers are approximately of the order of 1000-10000 ohms. In place of parallel damping there may also be used series dampings l0 and l I, which may conveniently be of the order of 10-100 ohms, and may also be replaced by windings constructed from resistance wire.

In the stated frequency example the dimensions, therefore, may conveniently be as follows:

Natural wave, primary=460 m., carrier wave: 150 m., longest side bandwave=200 m., shortest side band wave=120 m., secondary natural wave= m.

I claim:

l. A high frequency transformer providing a uniform transmission of a wide band of frequencies, having a primary and a secondary winding, said windings having natural frequen- 4O,

cies situated at the two limits of the frequency band to be transmitted; damping resistances being connected across said primary winding and said secondary winding, said damping resistances being smaller thanthe resonance resistance but 45,

greater than the effective impedance between the appertaining windings.

2. A high frequency transformer providing a uniform transmision of a wide band of frequencies, having a primary and a secondary 50 winding, said windings having natural frequencies situated at the two limits of the frequency band to be transmitted, damping resistances being connected across said primary winding and said secondary winding, said damping resistances 55 being in the order of A of the resonance resistance of said windings.

3. In an electrical circuit, a source of energy for supplying a signal covering a frequency band of at least one megacycle, a load circuit for utilizing the energy supplied from the source, a high frequency transformer for providing a uniform transmission of the said band of frequencies from the source to the load, said transformer having primary and secondary windings with the natural frequency of the primary winding being outside the frequency band to be transmitted from the source and the natural frequency of the secondary winding also being outside the frequency band to be transmitted from the source, and the natural resonant frequencies of the primary and secondary windings also being at opposite ends of the frequency band to be transmitted from the source to the load.

4. In a relay circuit, a source of signal energy for supplying signal energy covering a frequency band of at least the order of one megacycle, a load circuit, a high frequency transformer providing a substantially uniform transmission of the said band of frequencies of the source for coupling the source to the load circuit, said transformer having a primary and a secondary winding, the natural frequency of said primary winding being lower than the lowest frequency in the range of the supply source, and the natural frequency of said secondary winding being higher than the highest frequency in the range of the supply source.-

5. In a relay circuit, a source of signal energy for supplying signal energy covering a frequency band of at least the order of one megacycle, a load circuit, a high frequency transformer providing a substantially uniform transmission of the said band of frequencies of the source for coupling the source to the load circuit, said trans former having a primary and a secondary winding, the natural frequency of said primary winding being higher than the highest frequency in the range of the supply source, and the natural frequency of said secondary winding being lower than the lowest frequency in the range of the supply source.

6. In a relay circuit, a source of signal energy for supplying signal energy covering a frequency band of at least the order of one megacycle, a load circuit, a high frequency transformer providing a substantially uniform transmission of the said band of frequencies of the source for coupling the source to the load circuit, said transformer having a primary and a secondary winding, the natural frequency of said primary winding being lower than 0.8 times the lowest frequency in the frequency range to be transmitted from the source to the load and the natural frequency of said secondary winding being higher than 1.2 times the highest frequency in the frequency range to be transmitted from the source to the load.

7. In a relay circuit, a source of signal energy for supplying signal energy covering a frequency band of at least the order of one megacycle, a load circuit, a high frequency transformer providing a substantially uniform transmission of the'said band of frequencies of the source for coupling the source to the load circuit, said transformer having a primary and'a secondary winding, the natural frequency of said primary winding being higher than 1.2 times the highest frequency in the frequency range to be transmitted from the source to the load and the natural frequency of said secondary winding being lower than 0.8 times the lowest frequency in the frequency range to be transmitted from the source to the load.

8. The electrical circuit claimed in claim 3 comprising, in addition, damping resistance means associated with the primary and secondary windings, said damping resistances being smaller than the resonant resistances and greater than the effective impedance between the windings.

9. The electrical circuit claimed in claim 3, comprising, in addition, a damping resistance consisting of resistance wire forming the transformer primary and secondary windings.

10. In an amplifier circuit for amplifying a wide band of frequencies, a signal input source for supplying signals covering a frequency band of the order of at least one megacycle, a load circuit for utilizing the supplied frequencies, a transformer for coupling the signal input source and the load circuit, said transformer being adapted to pass substantially uniformly all frequencies of the supply source extending between the predetermined minimum frequency of the one megacycle supply range and the predetermined maximum value of the supply frequency range, said transformer having a primary winding with a natural resonant period at a frequency value outside of and to one side of the pass-band corresponding substantially to the supplied frequency range and said transformer having a secondary winding with a natural resonant period at a frequency also outside of and to the opposite side of the pass-band corresponding substantially to the supplied frequency range.

11. An electrical network for substantially undistortedly transferring a wide frequency band of signal energy wherein the transferred frequencies extend between predetermined limiting maximum and minimum frequency values separated from each other by a separation of the order of at least one megacycle, comprising a source of signal energy for supplying signals covering a frequency band of the order of a megacycle, a load circuit for utilizing the signal energy supplied by the source, and a coupling circuit including a transformer for supplying signals from the source to the load circuit, said transformer including primary and secondary windings for supplying the input signals from the source to the load circuit throughout a passband including all frequency values between the said predetermined minimum and maximum frequencies, said transformer having a peak response at one frequency value less than the minimum predetermined frequency and a second peak response at a frequency greater than the said maximum predetermined frequency.

12. The electrical network claimed in claim 11 comprising, in addition, damping resistance means associated with each of the primary and secondary windings of said transformer for providing substantially uniform response within the predetermined pass-band.

KURT SCHLESINGER. 

